Sulfur-containing compounds in gasoline and diesel oil convert to sulfur oxides (SOx) after combustion, leading to the formation of acid rain when emitted into the atmosphere. Furthermore, sulfur oxides in automobile tail-gas would result in an irreversible poisoning of the catalyst for automobile tail-gas conversion which greatly lowers the efficiency of the automobile tail-gas converter for conversion of nitrogen oxide (NOx), unburned hydrocarbons, particulates and the like, and thereby severely pollutes the environment. Therefore, lowering the content of sulfur in gasoline and diesel oil is one of the effective ways to improve the quality of the air and solve the environmental problem.
To achieve the standard of low sulfur gasoline and diesel oil, the commonly used processes for the desulfurization of gasoline and diesel oil include dethiolation by catalytic oxidation and catalytic hydrodesulfurization. The dethiolation process by catalytic oxidation can only remove thiols, but has no removing effect on relatively large amounts of thiophenes in gasoline and benzothiopbenes in diesel oil. In addition, the dethiolation process by catalytic oxidation has a problem of treatment of the harmful liquid waste and disulfides. Catalytic hydrodesulfurization needs high temperature, high pressure and hydrogen atmosphere, so the investment on the equipment and operating cost are high. Moreover, this process causes a loss of octane number of gasoline during the treatment and consumes a great amount of hydrogen.
Aromatics derived from oil refining and coal coking such as benzene, toluene, ethyl benzene, xylene, and aromatics higher than C9, also contain a small amounts of organic sulfides such as thiols, thioethers, thiophene, alkyl thiophenes, benzothiophenes, etc. The presence of these organic sulfides affects the quality of the aromatics and has a harmful effect on their applications. For example, the sulfur in feedstock benzene may cause the deactivation of the ruthenium catalyst for hydrogenation in the partial hydrogenation of benzene to cyclohexene, when C9 or C10 aromatics are used as a working solvent in the production of hydrogen peroxide using the anthraquinone process, the sulfur therein may cause the deactivation of the hydrogenation catalyst.
Removing sulfides in gasoline, diesel oil or aromatics using adsorptive process is a novel technology, which makes use of the adsorption selectivity of the adsorbent to the polar sulfides such as thiols, thiophene, etc, to remove the sulfides from gasoline, diesel oil or aromatics. Adsorptive desulfurization not only has the benefits of little investment, simple technology, but also has the advantages of little loss in the yield and octane number of gasoline, no consumption of hydrogen, no need of severe reaction conditions such as high temperature and high pressure when compared with the traditional desulfurization method by either oxidation or hydrogenation used for gasoline and diesel oil. The major types of adsorbents for desulfurization of gasoline and diesel oil reported presently are: oxide adsorbents (γ-Al2O3, TiO2, ZrO2, ZnO, SiO2), oxide adsorbents supporting metals (Ni, Na, K, Ca, Ba), molecular sieve adsorbents (A, X, Y, TS-1, SAPO-34, MCM-41), and ion-exchanged molecular sieve adsorbents, etc. The adsorbents used in the desulfurization of aromatics are mainly supported-type oxide adsorbents supporting metals (Ni, Pd, Pt, Cu, etc), as those disclosed in U.S. Pat. No. 2,876,196, U.S. Pat. No. 3,485,884, U.S. Pat. No. 4,419,224, U.S. Pat. No. 4,592,829, etc.
U.S. Pat. No. 6,221,280 discloses that Raney nickel can be used as an adsorbent to remove thiophene sulfur remained in hydrocarbon fuels after hydrodesulfurization.
As far as the present inventor knows, there has no report on the amorphous alloy with nickel as a major active component of the adsorbent for adsorptive desulfurization as yet.